Replacement disk to the My Book Pro II

Welcome.

He died on me a disc in the set. (WD20000C033-001 WDG2TP200002 TB (2000 GB) 

I need to replace the disk. To avoid trouble I have to mention two at a time.

I’m looking and looking solutions and I can not find.

1. What today discs I put in this device? 

2. Is this exchange with the new drives can increase thecapacity of 2 (2x1TB) to 4 TB (2x2TB)? 
 

Greetings to all!
Mariusz

It is recommended to replace the drives inside of the enclosure with the same model or similar one. If this drive uses Caviar Green, then you need to get Caviar Green drives. 

Regarding your second question, as far as I know, you cannot use drives of bigger size, meaning that you cannot increase the capacity of the device.